It has been known to change a conveyance speed of a conveyance roller that conveys for example paper in an image forming apparatus.
For example, a disclosed paper conveyance device switches the conveyance speed between two levels by performing intermittent operations of two intermediate roller clutches so as to be reversed from each other (see Patent Literature 1). Specifically, a first intermediate roller clutch intermits transmission of power from a motor to a first intermediate roller. A second intermediate roller clutch intermits transmission of the power from the motor to a second intermediate roller. By performing the intermittent operations of the two intermediate roller clutches so as to be reversed from each other, it is possible to switch constant speed driving not through an acceleration mechanism and acceleration driving through the acceleration mechanism.
The paper conveyance device disclosed in Patent Literature 1 is described to be capable of improving freedom of arrangement since there is no need to secure a large space for arrangement in the vicinity of an end of a rotary shaft of a roller.